This add-on is not compatible with your version of Firefox because of the following:

Version 7.6.2
Released September 2, 2010
102.4 kB
Works with
Firefox 2.0 - 4.0b5pre

7.6.2: - Added support for Chrome Preferences' save/retrieval of values - Fixed setting window dimention code. 7.6: - Added default size if preference was not set (also works for Chrome initial size) 7.5.1: - Added content padding - Fixed content height when show/hide title bar 7.5: - Fine tuned the fix in 7.4. The width and height was still a bit off. This fix makes it much better. 7.4: - Fixed window overlapping border issue 7.3: - Set default auto refresh to false, so the users need to turn it on if they want to 7.2: - Added code to refresh page only if the user is not active (not moving the mouse) 7.1: - Added auto reload of page and preference for setting interval and disable the feature